A time series of Landsat 8 images at Gulf of Laganas, Zakynthos Island, GreeceLANDSAT 8 OLIP

Using the Panchromatic band for water column correction to derive water depth and spectral bottom signature: Landsat 8 OLIP bandset used for this workPurple=1, Blue=2, Green=3, PAN=4, Red=5, NIR=6and SWIR1=7

Using pan sharpened images in this study Pan sharpening using Rstudio Brovey method

ZLand In order to test 4SM against spectral variations of the bottom substrate, I can enforce a depth over land to apply the water column attenuation from image calibration, then process these "artificial shallow" pixels to see how well/bad this depth is retrieved.

Result of this exercise From very shallow to very deep, the algorithm yields a surprisingly good estimation of depth; there is hardly any increase in uncertainty as depth increases.

Noise But, wait: this does not include the quantization noise (mmm...)! I tried including 8_bits quantization of the computation of "artificial" pixels: absolutely NO change either of av_Z4SM or std_Z4SM for Zland=20m.

GSD=15 m, pan-sharpened. NO smoothing applied. Just the estimated depth is "noisy", as an expression of

the reductive assumption on the Soil Line.

the pansharpening process : co-registration MULTI/PAN.

PAN solution I suppose that this good result is in part a marked benefit of using the PAN band.

Add heterogeneous atmosphere/water This does not account for the effect of the natural variations of the water/atmosphere optical properties, which can be very nasty in their own right, and increase dramatically deeper than ~half of the shallow depth range.